1. Field of the Invention
The present invention relates to a portable electronic device and a control method for the portable electronic device, and more specifically, it relates to a power supply control technique in an electronically controlled portable timepiece that incorporates a power generating mechanism.
2. Description of the Related Art
Recently, small-sized electronic timepieces in the form of, e.g., wristwatches have been developed. These timepieces incorporate a power generator such as a solar cell and operate without replacing batteries. These electronic timepieces charge large-capacitance capacitors with electric power generated by power generators, and indicate the time of day with the power discharged from the capacitors when power is not generated. These electronic timepieces can therefore operate stabily for a long time without batteries. Given the inconvenience of replacing batteries and problems incidental to disposal of exhausted batteries, it is expected that power generators will be incorporated in more and more electronic timepieces in the future.
In such an electronic timepiece incorporating a power generator, a limiter circuit for limiting a source voltage is provided to prevent a voltage generated by the power generator from exceeding the voltage tolerance level of a power supply unit having an electricity accumulating function, e.g., a large-capacitance capacitor, or to prevent a source voltage applied from the power supply unit to a time indicating circuit from exceeding the voltage tolerance level of the time indicating circuit.
In order to prevent a voltage generated by the power generator from exceeding the voltage tolerance level of the power supply unit, or prevent a source voltage applied from the power supply unit to the time indicating circuit from exceeding the withstanding voltage tolerance level of the time indicating circuit, the limiter circuit operates to electrically disconnect the power supply unit from the power generator at a point upstream of the power supply unit, or electrically disconnects the power supply unit from the time indicating circuit at a point downstream of the power supply unit, or short-circuits the output terminals of the power supply unit to prevent the generated voltage from being transmitted to downstream components.
However, in order to provide a stable power supply, an electronic timepiece incorporating a power generator is constructed such that when the power generator does not generate power for a predetermined time or longer, this condition is detected to shift the operation mode from a normal operation mode (indicating mode) in which the time of day is indicated, to a power-saving mode in which the time of day is not indicated.
Operating the limiter circuit requires a voltage detecting circuit for detecting the applied voltage, and the voltage detecting circuit increases power consumption. Particularly, when the voltage detecting circuit is constructed of a circuit for detecting voltage with high precision, there arises a problem of increasing both the circuit scale and power consumption.
Further, in order to prolong the operating time, an electronic timepiece incorporating a power generator includes a voltage step-up circuit for stepping up a source voltage to produce voltages for driving downstream circuits. However, unless a step-up factor of the voltage step-up circuit is correctly set, a voltage exceeding the voltage value suitable for operation or the absolute rated voltage is applied to the circuits, and in the worst case, the electronic timepiece would be damaged.
Therefore, it is an object of the present invention to overcome the aforementioned problems.
Accordingly, the object of the present invention is to realize a reliable power supply control function in a portable electronic device which includes a limiter circuit for limiting a source voltage, or includes the limiter circuit and a voltage step-up circuit, and to provide a portable electronic device and a control method for the portable electronic device with which power consumption can be reduced.
To solve the problems set forth above, a portable electronic device according to the present invention comprises a power generator or generating means for generating power through conversion from first energy to second energy in the form of electrical energy; a power supply or power supply means for accumulating the electrical energy produced by the power generation; a for accumulating the electrical energy produced by the power generation; a driven unit or means driven with the electrical energy supplied from the power supply; a power-generation detector or detecting means for detecting whether or not power is generated by the power generator; limiter-ON-voltage detector or detecting means for detecting whether or not a voltage generated by the power generator or a voltage accumulated in the power supply exceeds a preset limiter-ON voltage; a limiter or limiter means for limiting the voltage of the electrical energy to be supplied to the power supply to a predetermined reference voltage set in advance when it is determined, based on a detection result of the limiter-ON-voltage detector, that the voltage generated by the power generator or the voltage accumulated in the power supply has not been reduced below the preset limiter-ON voltage; and limiter-ON-voltage detection prohibiting unit or means for prohibiting the detecting operation of the limiter-ON-voltage detector when it is determined, based on a detection result of the power-generation detector, that power is not generated by the power generating means.
Also, the limiter-ON-voltage detection prohibiting unit may include an operation stopping unit or means for stopping operation of the limiter-ON-voltage detector to prohibit the detecting operation of the limiter-ON-voltage detector.
In addition, the portable electronic device may further comprise a generated-voltage detector or detecting means for detecting a voltage generated by the power generator, and the limiter-ON-voltage detection prohibiting unit may include a limiter-ON-voltage detection controller or control means for prohibiting the detecting operation of the limiter-ON-voltage detector when it is determined, based on a detection result of the generated-voltage detector, that the generated voltage does not exceed a predetermined limiter control voltage that is lower than the limiter-ON voltage, and allowing the detecting operation of the limiter-ON-voltage detector when the generated voltage exceeds the predetermined limiter control voltage.
Further, the portable electronic device according to the present invention may further comprise a limiter-ON unit or means for bringing the limiter into an operative state when it is determined, based on the detection result of the limiter-ON-voltage detector, that the voltage generated by the power generator or the voltage accumulated in the power supply has exceeded the preset limiter-ON voltage; and an operating-state controller or control means for bringing the limiter into an inoperative state when the limiter is in the operative state, and also when it is determined, based on the detection result of the power-generation detector, that power is not generated by the power generator or when it is determined, based on the detection result of the generated-voltage detector, that the generated voltage does not exceed the predetermined limiter control voltage that is lower than the limiter-ON voltage.
Also, the limiter-ON-voltage detector detects whether or not the voltage accumulated in the power supply means exceeds the preset limiter-ON voltage, with a cycle not larger than the cycle necessary for detecting a change of the voltage generated by the power generator.
A portable electronic device according to the present invention comprises a power generator or generating means for generating power through conversion from first energy to second energy in the form of electrical energy; a power supply or power supply means for accumulating the electrical energy produced by the power generation; a source-voltage stepping-up unit or means for stepping up a voltage of the electrical energy supplied from the power supply at a step-up factor n (where n is a real number larger than 1) and supplying the stepped-up voltage as driving power; a driven unit or means driven with the driving power supplied from the source-voltage stepping-up unit, a power-generation detector or detecting means for detecting whether or not power is generated by the power generator; a limiter-ON-voltage detector or detecting means for detecting whether or not at least one of a voltage generated by the power generator, a voltage accumulated in the power supply, and a voltage of the driving power after being stepped up exceeds a preset limiter-ON voltage; a limiter unit or means for limiting the voltage of the electrical energy to be supplied to the power supply to a predetermined reference voltage set in advance, when it is determined, based on a detection result of the limiter-ON-voltage detector, that at least one of the voltage generated by the power generator, the voltage accumulated in the power supply and the voltage of the driving power after being stepped up has not been reduced below the preset limiter-ON voltage; limiter-ON-voltage detection prohibiting unit or means for prohibiting the detecting operation of the limiter-ON-voltage detector when it is determined, based on a detection result of the power-generation detector, that power is not generated by the power generator; and step-up factor changing unit or means for setting the step-up factor n to nxe2x80x2 (where nxe2x80x2 is a real number and satisfies 1xe2x89xa6nxe2x80x2 less than n) when it is determined, based on a detection result of the limiter-ON-voltage detector, that at least one of the voltage generated by the power generator, the voltage accumulated in the power supply and the voltage of the driving power after being stepped up has not been reduced below the preset limiter-ON voltage, and also when the source-voltage stepping-up unit is performing step-up operation.
Also, the step-up factor changing unit may include a time-lapse determining unit or means for determining whether or not a predetermined factor-change prohibiting time, set in advance, has lapsed from the timing at which the step-up factor N was changed to Nxe2x80x2; and a change prohibiting unit or means for prohibiting a change of the step-up factor until the predetermined factor-change prohibiting time, set in advance, lapses from the timing at which the step-up factor N was changed to Nxe2x80x2.
Also, according to the present invention, a portable electronic device comprises a power generator or generating means for generating power through conversion from first energy to second energy in the form of electrical energy; a power supply or means for accumulating the electrical energy produced by the power generator; a source-voltage stepping-up/down unit or means for stepping up or down a voltage of the electrical energy supplied from the power supply at a step-up/down factor n (when n is a positive real number) and supplying the stepped-up/down voltage as driving power; a driven unit or means driven with the driving power supplied from the source-voltage stepping-up/down unit; a power-generation detector or detecting means for detecting whether or not power is generated by the power generator; a limiter-ON-voltage detector or detecting means for detecting whether or not at least one of a voltage generated by the power generator, a voltage accumulated in the power supply and a voltage of the driving power after being stepped up or down exceeds a preset limiter-ON voltage; a limiter or limiter means for limiting the voltage of the electrical energy to be supplied to the power supply to a predetermined reference voltage, set in advance, when it is determined, based on a detection result of the limiter-ON-voltage detector that at least one of the voltage generated by the power generator, the voltage accumulated in the power supply and the voltage of the driving power after being stepped up or down has not been reduced below the preset limiter-ON voltage; a limiter-ON-voltage detection prohibiting unit or means for prohibiting the detecting operation of the limiter-ON-voltage detector when it is determined, based on a detection result of the power-generation detector, that power is not generated by the power generator; and a step-up/down factor changing unit or means for setting the step-up factor n to nxe2x80x2 (where nxe2x80x2 is a positive real number and satisfies nxe2x80x2 less than n) when it is determined, based on a detection result of the limiter-ON-voltage detector, that at least one of the voltage generated by the power generator, the voltage accumulated in the power supply and the voltage of the driving power after being stepped up or down is not lower than the preset limiter-ON voltage.
According to another aspect of the invention, the step-up/down factor changing includes a time-lapse determining unit or means for determining whether or not a predetermined factor-change prohibiting time, set in advance, has lapsed from the timing at which the step-up/down factor N was changed to Nxe2x80x2; and a change prohibiting unit or means for prohibiting a change of the step-up/down factor until the predetermined factor-change prohibiting time set in advance lapses from the timing at which the step-up/down factor N was changed to Nxe2x80x2.
According to another aspect of the invention, the source-voltage stepping-up/down unit has a number M (M is an integer not less than 2) of step-up/down capacitors for step-up/down operation; and in the step-up/down operation, a number L (where L is an integer not less than 2 but not more than M) of ones among the number M of step-up/down capacitors are connected in series to be charged with the electrical energy supplied from the power supply, and the number L of step-up/down capacitors are then connected in parallel to produce a voltage lower than the electrical energy supplied from the power supply, the produced lower voltage being used as a voltage after the step-down operation or as a part of a voltage after the step-up operation.
According to another aspect of the invention, the portable electronic device further comprises a limiter controller or control means for bringing the limiter into an inoperative state when power is not generated by the power generator.
According to another aspect of the invention, the portable electronic device further comprises a limiter controller or control means for bringing the limiter into an inoperative state when an operating mode of the portable electronic device is in a power-saving mode.
According to another aspect, the power-generation detector detects whether or not power is generated, in accordance with a level of the generated voltage and a duration of power generation by the power generator.
According to another aspect of the present invention, a portable electronic device comprises a power generator or generating means for generating power through conversion from first energy to second energy in the form of electrical energy; a power supply or power supply means for accumulating the electrical energy produced by the power generation; a driven unit or means driven with the electrical energy supplied from the power supply; a power-generation detector or detecting means for detecting whether or not power is generated by the power generator; a limiter-ON-voltage detector or detecting means for detecting whether or not a voltage generated by the power generator or a voltage accumulated in the power supply exceeds a preset limiter-ON voltage; a limiter or limiter means for limiting the voltage of the electrical energy to be supplied to the power supply to a predetermined reference voltage, set in advance, when it is determined based on a detection result of the limiter-ON-voltage detector that the voltage generated by the power generator or the voltage accumulated in the power supply has not been lowered below the preset limiter-ON voltage, and a limiter controller or control means for bringing the limiter means into an inoperative state when power is not generated.
According to another aspect of the present invention, a portable electronic device comprises a power generator or generating means for generating power through conversion from first energy to second energy in the form of electrical energy; a power supply or power supply means for accumulating the electrical energy produced by the power generation; a source-voltage transforming unit or means for transforming a voltage of the electrical energy supplied from the power supply means and supplying the transformed voltage as driving power; a driven unit or means driven with the driving power supplied from the source-voltage transforming unit; a transformation prohibiting unit or means for prohibiting operation of the source-voltage transforming when the voltage of the power supply is lower than a predetermined voltage, set in advance, and also when the amount of power generated by the power generator is smaller than a predetermined amount of power set in advance; an accumulated-voltage detector or detecting means for detecting a voltage during or after voltage accumulation in the power supply when the operation of the source-voltage transforming is unit prohibited; and a transforming factor control unit or means for setting, in accordance with the voltage during or after the voltage accumulation in the power supply, a transforming factor used after the operation-prohibited state of the source-voltage transforming unit is released.
According to another aspect, the driven unit includes a time-measuring unit or means for indicating the time of day.
According to another aspect of the present invention, for an portable electronic device comprising a power generating device for generating power through conversion from first energy to second energy in the form of electrical energy, a power supply device for accumulating the electrical energy produced by the power generation, and a driven device driven with the electrical energy supplied, from the power supply device, a control method comprises a power-generation detecting step of detecting whether or not power is generated by the power generating device; a limiter-ON-voltage detecting step of detecting whether or not a voltage generated by the power generating device or a voltage accumulated in the power supply device exceeds a preset limiter-ON voltage; a limiting step of limiting the voltage of the electrical energy to be supplied to the power supply device to a predetermined reference voltage set in advance when it is determined, based on a detection result in the limiter-ON-voltage detecting step, that the voltage generated by the power generating device or the voltage accumulated in the power supply device has not been reduced below the preset limiter-ON voltage; and a limiter-ON-voltage detection prohibiting step of prohibiting the detecting operation in the limiter-ON-voltage detecting step when it is determined, based on a detection result in the power-generation detecting step, that power is not generated by the power generating device.
In a further aspect of the invention, in a control method for a portable electronic device comprising a power generating device for generating power through conversion from first energy to second energy in the form of electrical energy, a power supply device for accumulating the electrical energy produced by the power generation, a source-voltage stepping-up device for stepping up a voltage of the electrical energy supplied from the power supply device at a step-up factor N (where N is a real number larger than 1) and supplying the stepped-up voltage as driving power, and a driven device driven with the driving power supplied from the source-voltage stepping-up device, the method comprises a power-generation detecting step of detecting whether or not power is generated by the power generating device; a limiter-ON-voltage detecting step of detecting whether or not at least one of a voltage generated by the power generating device, a voltage accumulated in the power supply device and a voltage of the driving power after being stepped up exceeds a preset limiter-ON voltage; a limiting step of limiting the voltage of the electrical energy to be supplied to the power supply device to a predetermined reference voltage, set in advance, when it is determined based on a detection result in the limiter-ON-voltage detecting step that at least one of the voltage generated by the power generating device, the voltage accumulated in the power supply device and the voltage of the driving power after being stepped up has not been reduced below the preset limiter-ON voltage; a limiter-ON-voltage detection prohibiting step of prohibiting the detecting operation in the limiter-ON-voltage detecting step when it is determined, based on a detection result in the power-generation detecting step, that power is not generated by the power generating device; and a step-up factor changing step of setting the step-up factor N to Nxe2x80x2 (where Nxe2x80x2 is a real number and satisfies 1xe2x89xa6Nxe2x80x2 less than N) when it is determined based on a detection result in the limiter-ON-voltage detecting step that at least one of the voltage generated by the power generating device, the voltage accumulated in the power supply device and the voltage of the driving power after being stepped up has not been reduced below the preset limiter-ON voltage, and also when the source-voltage stepping-up device is performing a step-up operation.
In another aspect, in a control method for a portable electronic device comprising a power generating device for generating power through conversion from first energy to second energy in the form of electrical energy, a power supply device for accumulating the electrical energy produced by the power generation, a source-voltage stepping-up/down device for stepping up or down a voltage of the electrical energy supplied from the power supply device at a step-up factor n (where n is a positive real number) and supplying the stepped-up/down voltage as driving power, a driven device driven with the driving power supplied from the source-voltage stepping-up/down device, and a power-generation detecting device for detecting whether or not power is generated by the power generating device, the method comprises a limiter-ON-voltage detecting step of detecting whether or not at least one of a voltage generated by the power generating device, a voltage accumulated in the power supply device and a voltage of the driving power after being stepped up or down exceeds a preset limiter-ON voltage; a limiting step of limiting the voltage of the electrical energy to be supplied to the power supply device to a predetermined reference voltage set in advance when it is determined based on a detection result in the limiter-ON-voltage detecting step that at least one of the voltage generated by the power generating device, the voltage accumulated in the power supply device and the voltage of the driving power after being stepped up or down has not been reduced below the preset limiter-ON voltage; a limiter-ON-voltage detection prohibiting step of prohibiting the detecting operation in the limiter-ON-voltage detecting step when it is determined based on a detection result of the power-generation detecting device that power is not generated by the power generating device; and a step-up/down factor changing step of setting the step-up factor n to nxe2x80x2 (where nxe2x80x2 is a positive real number and satisfies nxe2x80x2 less than n) when it is determined based on a detection result in the limiter-ON-voltage detecting step that at least one of the voltage generated by the power generating device, the voltage accumulated in the power supply device and the voltage of the driving power after being stepped up or down has not been reduced below the preset limiter-ON voltage.
In another aspect, in a control method for a portable electronic device comprising a power generating device for generating power through conversion from first energy to second energy in the form of electrical energy, a power supply device for accumulating the electrical energy produced by the power generation, a source-voltage transforming device for transforming a voltage of the electrical energy supplied from the power supply device and supplying the transformed voltage as driving power, and a driven device driven with the driving power supplied from the source-voltage transforming device, the method comprises a transformation prohibiting step of prohibiting operation of the source-voltage transforming device when the voltage of the power supply device is lower than a predetermined voltage set in advance, and also when the amount of power generated by the power generating device is smaller than a predetermined amount of power set in advance; an accumulated-voltage detecting step of detecting a voltage during or after voltage accumulation in the power supply device when the operation of the source-voltage transforming device is prohibited; and a transforming factor control step of setting, in accordance with the voltage during or after the voltage accumulation in the power supply device, a transforming factor used after the operation-prohibited state of the source-voltage transforming device is released.
Other objects and attainments together with a fuller understanding of the invention will become apparent and appreciated by referring to the following description and claims taken in conjunction with the accompanying drawings.